CN110998377A

CN110998377A - Optical filter and information terminal with camera

Info

Publication number: CN110998377A
Application number: CN201880048867.0A
Authority: CN
Inventors: 久保雄一郎
Original assignee: Nippon Sheet Glass Co Ltd
Current assignee: Nippon Sheet Glass Co Ltd
Priority date: 2017-07-27
Filing date: 2018-06-12
Publication date: 2020-04-10
Anticipated expiration: 2038-06-12
Also published as: US20200233130A1; TWI739011B; KR102303331B1; US20230152502A1; JP6267823B1; JP2019028163A; WO2019021666A1; US11585968B2; KR20200030602A; CN110998377B; TW201910895A

Abstract

The optical filter (1a) is provided with a light absorption layer (10) and satisfies the following conditions (i) to (iii) when light having a wavelength of 300nm to 1200nm is incident at an incident angle of 0 deg. (i) An average transmittance of 78% or more at a wavelength of 450 to 600 nm; (ii) a spectral transmittance of 1% or less at a wavelength of 750nm to 1080 nm; and (iii) a spectral transmittance at a wavelength of 600nm to 750nm that decreases with increasing wavelength and a first IR cut-off wavelength that exists in a range of 620nm to 680 nm. The condition (i), the condition (ii), and the condition (iii) are satisfied by the light-absorbing layer (10).

Description

Optical filter and information terminal with camera

Technical Field

The present invention relates to an optical filter and an information terminal with a camera.

Background

In an imaging Device using an imaging element such as a CCD (Charge Coupled Device) or a CMOS (complementary metal Oxide Semiconductor), various optical filters are arranged in front of the imaging element in order to obtain an image with good color reproducibility. In general, an image pickup element has spectral sensitivity in a wide wavelength range from an ultraviolet region to an infrared region. On the other hand, the human visual acuity exists only in the region of visible light. Therefore, in order to make the spectral sensitivity of an imaging device in an imaging apparatus close to the human visual sensitivity, a technique is known in which an optical filter for shielding infrared rays is disposed in front of the imaging device.

As the optical filter, there are an optical filter that reflects light such as an optical filter having a dielectric multilayer film, and an optical filter that absorbs light such as an optical filter having a film containing a light absorbing agent capable of absorbing light of a predetermined wavelength. The latter is preferable in that it has spectral characteristics that are less likely to vary with the incident angle of incident light.

For example, patent document 1 describes a near-infrared absorption filter formed of a near-infrared absorbent and a resin. The near-infrared absorber is obtained from a prescribed phosphonic acid compound, a prescribed phosphate ester compound and a copper salt. The specified phosphonic acid compounds having a radical-CH bonded to the phosphorus atom P₂CH₂-R¹¹A monovalent group R¹。R¹¹Represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a fluoroalkyl group having 1 to 20 carbon atoms.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2011-

Disclosure of Invention

Problems to be solved by the invention

The near infrared absorption filter described in patent document 1 can effectively absorb light having a wavelength of 800nm to 1200nm, but it is hard to say that it has a desired light absorption characteristic at a wavelength of 650nm to 800 nm. Accordingly, the present invention provides an optical filter capable of exhibiting desired optical performance, which is difficult to achieve only with the near-infrared absorption filter described in patent document 1, with a simple configuration.

Means for solving the problems

The present invention provides an optical filter, wherein,

the optical filter is provided with a light absorption layer,

when light with the wavelength of 300 nm-1200 nm is incident at the incident angle of 0 degree,

(i) has an average transmittance of 78% or more at a wavelength of 450 to 600nm,

(ii) has a spectral transmittance of 1% or less at a wavelength of 750nm to 1080nm,

(iii) has a spectral transmittance that decreases with increasing wavelength at a wavelength of 600nm to 750nm, and a first IR cut-off wavelength that exhibits a spectral transmittance of 50% at a wavelength of 600nm to 750nm exists in a range of 620nm to 680nm,

the optical filter satisfies the condition (i), the condition (ii), and the condition (iii) by the light absorbing layer.

Effects of the invention

The optical filter can exhibit desired optical performance with a simple configuration.

Drawings

Fig. 1A is a cross-sectional view showing an example of an optical filter of the present invention.

Fig. 1B is a cross-sectional view showing another example of the optical filter of the present invention.

Fig. 1C is a cross-sectional view showing another example of the optical filter of the present invention.

Fig. 1D is a cross-sectional view showing another example of the optical filter of the present invention.

Fig. 1E is a cross-sectional view showing another example of the optical filter of the present invention.

Fig. 2 is a cross-sectional view showing an example of a camera module including the optical filter of the present invention.

Fig. 3 is a transmittance spectrum of the optical filter of example 1.

Fig. 4 is a transmittance spectrum of the optical filter of example 2.

FIG. 5 is a transmittance spectrum of the optical filter of example 16.

FIG. 6 is a transmittance spectrum of an optical filter of example 17.

FIG. 7 is a transmittance spectrum of the optical filter of example 20.

FIG. 8 is a transmittance spectrum of an optical filter of example 21.

FIG. 9 is a transmittance spectrum of an optical filter of example 22.

FIG. 10 is a transmittance spectrum of an optical filter of example 36.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description relates to examples of the present invention, and the present invention is not limited to these examples.

The optical filter is desired to have characteristics of transmitting light having a wavelength of 450nm to 600nm and having a cutoff wavelength of 650nm to 1100 nm. However, for example, the optical filter described in patent document 1 does not have sufficient light absorption characteristics at wavelengths of 650nm to 800nm, and requires a separate light absorption layer or light reflection film in order to cut off light at wavelengths of 650nm to 800 nm. Alternatively, a substrate such as infrared absorbing glass suitable for light having a cut-off wavelength of 650nm to 800nm needs to be used in combination. Thus, it is not easy to realize an optical filter having the above desired characteristics with a simple configuration (e.g., one light absorbing layer). Actually, the present inventors repeated trial and error for a plurality of times in order to realize an optical filter having the above desired characteristics with a simple configuration. As a result, the inventors finally studied the optical filter of the present invention.

As shown in fig. 1A, the optical filter 1A includes a light absorbing layer 10. The optical filter 1a satisfies the following conditions (i) to (iii) when light having a wavelength of 300nm to 1200nm is incident at an incident angle of 0 °. In the optical filter 1a, the light absorbing layer 10 satisfies the following condition (i), the following condition (ii), and the following condition (iii).

(i) An average transmittance of 78% or more at a wavelength of 450 to 600nm

(ii) Spectral transmittance of 1% or less at wavelength of 750nm to 1080nm

(iii) A spectral transmittance of 600nm to 750nm decreasing with increasing wavelength, and a first IR cut-off wavelength existing in a range of 620nm to 680nm

In the present specification, "spectral transmittance" refers to transmittance when incident light of a specific wavelength enters an object such as a sample, "average transmittance" refers to an average value of spectral transmittance in a predetermined wavelength range, and "maximum transmittance" refers to a maximum value of spectral transmittance in a predetermined wavelength range. In the present specification, the term "transmittance spectrum" refers to a spectrum in which spectral transmittances at respective wavelengths in a predetermined wavelength range are arranged in order of wavelength.

In the present specification, the "IR cut-off wavelength" refers to a wavelength at which, when light having a wavelength of 300nm to 1200nm is incident on an optical filter at a predetermined incident angle, the spectral transmittance of 50% is exhibited in a wavelength range of 600nm or more. The "first IR cut-off wavelength" is an IR cut-off wavelength when light is incident on the optical filter at an incident angle of 0 °. The "UV cut-off wavelength" refers to a wavelength at which, when light having a wavelength of 300nm to 1200nm is incident on the optical filter at a predetermined incident angle, the spectral transmittance is 50% in a wavelength range of 450nm or less. The "first UV cut-off wavelength" is a UV cut-off wavelength when light is incident on the optical filter at an incident angle of 0 °.

By making the optical filter 1a satisfy the above-described conditions (i) to (iii), the optical filter 1a can efficiently cut off light having a wavelength of 650nm to 1100nm while increasing the amount of light having a wavelength of 450nm to 600nm transmitted therethrough. Therefore, the transmittance spectrum of the optical filter 1a is more suitable for human visual acuity than the transmittance spectrum of the near infrared absorption filter described in patent document 1. The optical filter 1a satisfies the conditions (i) to (iii) by the light absorbing layer 10.

Regarding the above (i), the optical filter 1a preferably has an average transmittance of 80% or more, more preferably 82% or more at a wavelength of 450nm to 600 nm.

In the above (iii), the first IR cut wavelength is preferably in the range of 630nm to 650 nm. Thus, the transmittance spectrum of the optical filter 1a is more suitable for human visual acuity.

The optical filter 1a preferably satisfies the following condition (iv) when light having a wavelength of 300nm to 1200nm is incident at an incident angle of 0 °. Thus, the optical filter 1a can effectively cut off light in the ultraviolet region, and the transmittance spectrum of the optical filter 1a is more suitable for human visual acuity.

(iv) Spectral transmittance of 1% or less at a wavelength of 300 to 350nm

As for the above (iv), it is preferable that the condition (iv) is satisfied by the light absorbing layer 10 in the optical filter 1 a.

In the above (iv), the optical filter 1a preferably has a spectral transmittance of 1% or less at a wavelength of 300nm to 360nm when light having a wavelength of 300nm to 1200nm is incident at an incident angle of 0 °.

The optical filter 1a preferably satisfies the following condition (v) when light having a wavelength of 300nm to 1200nm is incident at an incident angle of 0 °. Thus, the transmittance spectrum of the optical filter 1a is more suitable for human visual acuity.

(v) Has a spectral transmittance that increases with increasing wavelength at a wavelength of 350nm to 450nm, and a first UV cut-off wavelength exists in a range of 380nm to 430 nm.

In the optical filter 1a, the condition (v) is preferably satisfied by the light absorption layer 10.

In the above (v), the first UV cut-off wavelength is preferably in the range of 390nm to 420nm in wavelength. Thus, the transmittance spectrum of the optical filter 1a is more suitable for human visual acuity.

The optical filter 1a preferably satisfies the following condition (vi) when light having a wavelength of 300nm to 1200nm is incident at an incident angle of 0 °. This enables shielding of infrared rays having a relatively long wavelength (wavelength of 1000 to 1100 nm). Conventionally, a light reflecting film formed of a dielectric multilayer film has been often used in order to cut off light of this wavelength. However, according to the optical filter 1a, light of the wavelength can be effectively cut off without using such a dielectric multilayer film. Even if a light reflection film composed of a dielectric multilayer film is required, the level of reflection performance required for the light reflection film can be reduced, and therefore the number of dielectric layers stacked in the light reflection film can be reduced, and the cost required for forming the light reflection film can be reduced. In the optical filter 1a, the condition (vi) is preferably satisfied by the light absorbing layer 10.

(vi) Spectral transmittance of less than 3% at a wavelength of 1000 to 1100nm

The optical filter 1a preferably satisfies the following condition (vii) when light having a wavelength of 300nm to 1200nm is incident at an incident angle of 0 °. In this case, infrared rays having a longer wavelength (1100 to 1200nm) can be cut off. Thus, the optical filter 1a can effectively cut off light of the wavelength without using a dielectric multilayer film or even with reducing the number of dielectric layers in the dielectric multilayer film. In the optical filter 1a, the light absorption layer 10 preferably satisfies the condition (vii).

(vii) A spectral transmittance of 15% or less at a wavelength of 1100 to 1200nm

For example, in the optical filter 1a, the absolute value of the difference between the second IR cut wavelength and the first IR cut wavelength is 10nm or less (condition (viii)). The second IR cut-off wavelength is an IR cut-off wavelength at which light having a wavelength of 300nm to 1200nm is incident on the optical filter 1a at an incident angle of 40 °. In this case, the transmittance characteristic of the optical filter 1a in the vicinity of the first IR cut wavelength is less likely to vary with respect to the incident angle of the light incident on the optical filter 1 a. As a result, the occurrence of different color tones in the center and the periphery of the obtained image can be suppressed by the imaging device in which the optical filter 1a is disposed in front of the imaging element.

In the optical filter 1a, the absolute value of the difference between the second IR cut wavelength and the first IR cut wavelength is preferably 5nm or less.

For example, in the optical filter 1a, the absolute value of the difference between the third IR cut wavelength and the first IR cut wavelength is 15nm or less (condition (ix)). The third IR cut-off wavelength is an IR cut-off wavelength at which light having a wavelength of 300nm to 1200nm is incident on the optical filter 1a at an incident angle of 50 °. In this case, even if the incident angle of the light incident on the optical filter 1a significantly changes, it is possible to suppress the change in the transmittance characteristic in the vicinity of the first IR cut wavelength of the optical filter 1 a. As a result, even if the optical filter 1a is disposed in front of the image pickup device of the image pickup apparatus capable of performing image pickup with a wide angle of view, a good image can be easily obtained.

For example, in the optical filter 1a, the absolute value of the difference between the fourth IR cut wavelength and the first IR cut wavelength is 20nm or less. The fourth IR cut-off wavelength is an IR cut-off wavelength at which light having a wavelength of 300nm to 1200nm is incident on the optical filter 1a at an incident angle of 60 °. In this case, even if the optical filter 1a is disposed in front of the image pickup device of the image pickup apparatus capable of performing image pickup with a wide angle of view, a good image can be easily obtained.

For example, in the optical filter 1a, the absolute value of the difference between the second UV cut wavelength and the first UV cut wavelength is 10nm or less (condition (x)). The second UV cut-off wavelength is a UV cut-off wavelength at which light having a wavelength of 300nm to 1200nm is incident on the optical filter 1a at an incident angle of 40 °. In this case, the transmittance characteristic of the optical filter 1a in the vicinity of the first UV cut wavelength is less likely to vary with respect to the incident angle of the light incident on the optical filter 1 a. As a result, the occurrence of different color tones in the center and the periphery of the obtained image can be suppressed by the imaging device in which the optical filter 1a is disposed in front of the imaging element.

In the optical filter 1a, the absolute value of the difference between the second UV cut wavelength and the first UV cut wavelength is preferably 5nm or less.

For example, in the optical filter 1a, the absolute value of the difference between the third UV cut wavelength and the first UV cut wavelength is 15nm or less (condition (xi)). The third UV cut-off wavelength is a UV cut-off wavelength at which light having a wavelength of 300nm to 1200nm is incident on the optical filter 1a at an incident angle of 50 °. In this case, even if the incident angle of light incident on the optical filter 1a significantly changes, it is possible to suppress a change in the transmittance characteristic of the optical filter 1a in the vicinity of the first UV cut wavelength. As a result, even if the optical filter 1a is disposed in front of the image pickup device of the image pickup apparatus capable of performing image pickup with a wide angle of view, a good image can be easily obtained.

For example, in the optical filter 1a, the absolute value of the difference between the fourth UV cut wavelength and the first UV cut wavelength is 20nm or less. The fourth UV cut-off wavelength is a UV cut-off wavelength at which light having a wavelength of 300nm to 1200nm is incident on the optical filter 1a at an incident angle of 60 °. In this case, even if the optical filter 1a is disposed in front of the image pickup device of the image pickup apparatus capable of performing image pickup with a wide angle of view, a good image can be easily obtained.

The optical filter 1a preferably satisfies the following condition (xii) when light having a wavelength of 300nm to 1200nm is incident at an incident angle of 0 °. In the optical filter 1a, the condition (xii) is preferably satisfied by the light absorbing layer 10.

(xii) A spectral transmittance of 0.5% or less, more preferably 0.1% or less at a wavelength of 800 to 950nm

The optical filter 1a preferably further satisfies the following condition (xiii) when light having a wavelength of 300nm to 1200nm is incident at an incident angle of 0 °. In the optical filter 1a, the condition (xiii) is preferably satisfied by the light absorbing layer 10.

(xiii) A spectral transmittance of 0.5% or less, more preferably 0.1% or less at a wavelength of 800 to 1000nm

Each color filter for RGB used in the imaging device may transmit not only light in a wavelength range corresponding to each RGB, but also light having a wavelength of 800nm or more. Therefore, if the spectral transmittance of the infrared cut filter used in the imaging device in the wavelength range is not reduced to a certain degree, light in the wavelength range enters a pixel of the imaging element and a signal is output from the pixel. When a digital image is obtained using such an imaging device, if the amount of light in the visible light range is sufficiently strong, even if infrared rays of low light amount are transmitted through the color filter and received by the pixels of the imaging element, the obtained digital image is not significantly affected. However, when the amount of light in the visible light region is small or in a dark portion of an image, such infrared rays are easily affected, and in this case, there is a possibility that the color tones of blue, red, and the like may be mixed in the image.

Thus, color filters used with image sensors such as CMOS and CCD may transmit light having a wavelength of 800 to 950nm or 800 to 1000 nm. Such a defect in the image can be prevented by making the optical filter 1a satisfy the conditions (xii) and (xiii) described above.

The light absorbing layer 10 is not particularly limited as long as it can absorb light in a predetermined wavelength range so that the optical filter 1a satisfies the conditions (i) to (iii) described above, and for example, the light absorbing layer 10 contains a light absorbing agent formed of phosphonic acid and copper ions.

In the case where the light absorbing layer 10 includes a light absorber formed of phosphonic acid and copper ions, the phosphonic acid includes, for example, a first phosphonic acid having an aryl group. The aryl group in the first phosphonic acid is bonded to the phosphorus atom. Thus, the optical filter 1a easily satisfies the conditions (i) to (iii) described above.

Examples of the aryl group of the first phosphonic acid include a phenyl group, a benzyl group, a tolyl group, a nitrophenyl group, a hydroxyphenyl group, a halophenyl group in which at least 1 hydrogen atom of the phenyl group is substituted with a halogen atom, and a halobenzyl group in which at least 1 hydrogen atom of the phenyl ring of the benzyl group is substituted with a halogen atom. Preferably, the first phosphonic acid has a halophenyl group in a portion thereof. In this case, the optical filter 1a easily and reliably satisfies the conditions (i) to (iii) described above.

In the case where the light absorbing layer 10 includes a light absorber formed of phosphonic acid and copper ions, the phosphonic acid preferably further includes a second phosphonic acid having an alkyl group. In the second phosphonic acid, an alkyl group is bonded to the phosphorus atom.

The alkyl group of the second phosphonic acid is, for example, an alkyl group having 6 or less carbon atoms. The alkyl group may have either of a straight chain and a branched chain.

When the light absorbing layer 10 contains a light absorbing agent formed of phosphonic acid and copper ions, the light absorbing layer 10 preferably further contains a phosphate ester for dispersing the light absorbing agent and a matrix resin.

The phosphate ester contained in the light absorbing layer 10 is not particularly limited as long as the light absorbing agent can be properly dispersed, and examples thereof includeSuch as a phosphoric acid diester represented by the following formula (c1) and a phosphoric acid monoester represented by the following formula (c 2). In the following formulae (c1) and (c2), R₂₁、R₂₂And R₃Are respectively- (CH)₂CH₂O)_nR₄The 1-valent functional group is represented by the formula, n is an integer of 1-25, R₄Represents an alkyl group having 6 to 25 carbon atoms. R₂₁、R₂₂And R₃Are functional groups of the same or different kinds from each other.

[ solution 1]

The phosphate ester is not particularly limited, and may be, for example, Plysurf a 208N: polyoxyethylene alkyl (C12, C13) ether phosphate, Plysurf a 208F: polyoxyethylene alkyl (C8) ether phosphate, Plysurf a 208B: polyoxyethylene lauryl ether phosphate, Plysurf a 219B: polyoxyethylene lauryl ether phosphate, Plysurf AL: polyoxyethylene styrenated phenyl ether phosphate, Plysurf a 212C: polyoxyethylene tridecyl ether phosphate, or Plysurf a 215C: polyoxyethylene tridecyl ether phosphate. These are all products manufactured by the first industrial pharmaceutical company. Additionally, the phosphate ester may be NIKKOL DDP-2: polyoxyethylene alkyl ether phosphate, NIKKOL DDP-4: polyoxyethylene alkyl ether phosphate, or NIKKOL DDP-6: polyoxyethylene alkyl ether phosphate ester. These are all products manufactured by Nikkol Chemicals.

The matrix resin included in the light absorbing layer 10 is, for example, a resin capable of dispersing the light absorbing agent and capable of being cured by heat or ultraviolet rays. When a 0.1mm resin layer is formed from the resin, the resin layer may have a transmittance of, for example, 70% or more, preferably 75% or more, and more preferably 80% or more, for a wavelength of 350nm to 900 nm. The content of the phosphonic acid is, for example, 3 to 180 parts by mass with respect to 100 parts by mass of the matrix resin.

The matrix resin contained in the light absorbing layer 10 is not particularly limited as long as the above properties are satisfied, and examples thereof include a (poly) olefin resin, a polyimide resin, a polyvinyl butyral resin, a polycarbonate resin, a polyamide resin, a polysulfone resin, a polyether sulfone resin, a polyamideimide resin, (modified) acrylic resin, an epoxy resin, and a silicone resin. The matrix resin is a silicone resin that may contain an aryl group such as a phenyl group, preferably an aryl group such as a phenyl group. If the light absorbing layer 10 is hard (hard), cracks are likely to be generated by curing shrinkage in the manufacturing process of the optical filter 1a as the thickness of the light absorbing layer 10 increases. When the matrix resin is a silicone resin containing an aryl group, the light absorbing layer 10 easily has good crack resistance. In addition, when the silicone resin containing an aryl group is used, the light absorber is likely to aggregate when the light absorber formed of phosphonic acid and copper ions is contained. When the matrix resin of the light absorbing layer 10 is a silicone resin containing an aryl group, the phosphate ester contained in the light absorbing layer 10 preferably has a flexible linear organic functional group such as an oxyalkyl group, like the phosphate ester represented by the formula (c1) or the formula (c 2). This is because the light absorbing agent is less likely to aggregate due to the interaction of the combination of the phosphonic acid, the silicone resin containing an aryl group, and the phosphate ester having a linear organic functional group such as an oxyalkyl group, and the light absorbing layer can have good rigidity and good flexibility. Specific examples of the silicone resin used as the matrix resin include KR-255, KR-300, KR-2621-1, KR-211, KR-311, KR-216, KR-212 and KR-251. These are all silicone resins manufactured by shin-Etsu chemical industries, Inc.

As shown in fig. 1A, the optical filter 1A further includes, for example, a transparent dielectric substrate 20. The transparent dielectric substrate 20 is covered with the light absorbing layer 10. The transparent dielectric substrate 20 is not particularly limited as long as it is a dielectric substrate having a high average transmittance (for example, 80% or more) at 450 to 600 nm.

The transparent dielectric substrate 20 is made of, for example, glass or resin. When the transparent dielectric substrate 20 is made of glass, the glass is, for example, borosilicate glass such as D263, white plate glass such as soda lime glass (cyan plate) or B270, alkali-free glass, or infrared-absorbing glass such as copper-containing phosphate glass or copper-containing fluorophosphate glass. When the transparent dielectric substrate 20 is an infrared-absorbing glass such as a copper-containing phosphate glass or a copper-containing fluorophosphate glass, the optical filter 1a can be provided with a required infrared absorption performance by a combination of the infrared absorption performance of the transparent dielectric substrate 20 and the infrared absorption performance of the light-absorbing layer 10. Examples of such an infrared-absorbing glass include BG-60, BG-61, BG-62, BG-63 and BG-67 manufactured by Schottky, 500EXL manufactured by Nippon Denko Junior, and CM5000, CM500, C5000 and C500S manufactured by HOYA. The infrared-absorbing glass may have ultraviolet absorption characteristics.

The transparent dielectric substrate 20 may be a crystalline substrate having transparency such as magnesium oxide, sapphire, or quartz. For example, sapphire is not easily scratched due to its high hardness. Therefore, a plate-shaped sapphire may be disposed as an abrasion-resistant protective material (protective filter) on the front surface of a camera module or a lens provided in a mobile terminal such as a smartphone or a mobile phone. By forming the light absorbing layer 10 on such a plate-shaped sapphire, light having a wavelength of 650nm to 1100nm can be effectively shielded while protecting the camera module and the lens. An optical filter having a shielding property for infrared rays having a wavelength of 650nm to 1100nm is not necessarily disposed around an image pickup device such as a CCD or a CMOS or inside a camera module. Therefore, if the light absorbing layer 10 is formed on the plate-shaped sapphire, it can contribute to the reduction of the back of the camera module.

When the transparent dielectric substrate 20 is made of a resin, the resin is, for example, a (poly) olefin resin, a polyimide resin, a polyvinyl butyral resin, a polycarbonate resin, a polyamide resin, a polysulfone resin, a polyether sulfone resin, a polyamideimide resin, (modified) acrylic resin, an epoxy resin, or a silicone resin.

The optical filter 1a can be manufactured by, for example, applying a composition for forming the light absorbing layer 10 (light absorbing composition) to one main surface of the transparent dielectric substrate 20 to form a coating film and drying the coating film. A method for producing the light absorbing composition and a method for producing the optical filter 1a will be described by taking as an example a case where the light absorbing layer 10 contains a light absorbing agent formed of phosphonic acid and copper ions.

First, an example of a method for producing the light absorbing composition will be described. A copper salt such as copper acetate monohydrate is added to a predetermined solvent such as Tetrahydrofuran (THF) and stirred to obtain a copper salt solution. Then, a phosphate compound such as a phosphoric acid diester represented by the formula (c1) or a phosphoric acid monoester represented by the formula (c2) is added to the copper salt solution and stirred to prepare a solution a. The first phosphonic acid is added to a predetermined solvent such as THF and stirred to prepare solution B. When two or more kinds of phosphonic acids are used as the first phosphonic acid, the phosphonic acids may be added to a predetermined solvent such as THF and stirred, and a plurality of kinds of preliminary solutions prepared for each kind of phosphonic acid may be mixed to prepare solution B. Preferably, an alkoxysilane monomer is added in the preparation of the solution B.

When the alkoxysilane monomer is added to the light absorbing composition, the particles of the light absorbing agent can be prevented from agglomerating with each other, and therefore the light absorbing agent in the light absorbing composition is well dispersed even if the content of the phosphate ester is reduced. In addition, when the optical filter 1a is manufactured using the light absorbing composition, the siloxane bond (-Si-O-Si-) can be formed by processing the composition so that the hydrolysis reaction and the polycondensation reaction of the alkoxysilane monomer sufficiently occur, and the optical filter 1a has good moisture resistance. In addition, the optical filter 1a has good heat resistance. This is because siloxane bonds are higher in energy and chemically more stable than bonds such as-C-bonds and-C-O-bonds, and are excellent in heat resistance and moisture resistance.

Next, while stirring the solution a, the solution B was added to the solution a, and stirring was performed for a predetermined time. Then, a predetermined solvent such as toluene is added to the solution and stirred to obtain a solution C. Then, the solution C is heated and desolventized for a predetermined time to obtain a solution D. Thus, components generated by dissociation of a copper salt, such as a solvent such as THF and acetic acid (having a boiling point of about 118 ℃ C.), are removed, and a light absorbing agent is generated from the first phosphonic acid and copper ions. The temperature at which the solution C is heated is determined based on the boiling point of the component to be dissociated and removed from the copper salt. In the solvent removal treatment, a solvent such as toluene (boiling point about 110 ℃ C.) used for obtaining the solution C is also volatilized. The solvent preferably remains in the light-absorbing composition to some extent, and therefore, the amount of the solvent to be added and the time for the solvent removal treatment may be determined in view of this. In order to obtain liquid C, o-xylene (boiling point: about 144 ℃ C.) may be used instead of toluene. In this case, the boiling point of o-xylene is higher than that of toluene, and therefore the amount of addition can be reduced to about one-fourth of that of toluene.

In the case where the light absorbing composition further comprises a second phosphonic acid, for example, solution H is further prepared as follows. First, a copper salt such as copper acetate monohydrate is added to a predetermined solvent such as Tetrahydrofuran (THF) and stirred to obtain a copper salt solution. Then, a phosphate compound such as a phosphoric acid diester represented by the formula (c1) or a phosphoric acid monoester represented by the formula (c2) is added to the copper salt solution and stirred to prepare a solution E. Further, the second diphosphonic acid is added to a predetermined solvent such as THF and stirred to prepare solution F. When two or more kinds of phosphonic acids are used as the second phosphonic acid, the second phosphonic acid may be added to a predetermined solvent such as THF and stirred, and a plurality of kinds of preliminary solutions prepared for each kind of the second phosphonic acid may be mixed to prepare solution F. While stirring the solution E, the solution F was added to the solution E and stirred for a predetermined time. Then, a predetermined solvent such as toluene is added to the solution and stirred to obtain solution G. Next, the solution G is heated and subjected to a solvent removal treatment for a predetermined time to obtain a solution H. Thereby, components generated by dissociation of the solvent such as THF and the like and the acetic acid and the like by the copper salt are removed, and another light absorbing agent is generated from the second phosphonic acid and the copper ion. The temperature for heating the solution G is determined in the same manner as the solution C, and the solvent for obtaining the solution G is also determined in the same manner as the solution C.

A light absorbing composition can be prepared by adding a matrix resin such as a silicone resin to the solution D and stirring. In addition, when the light absorbing composition contains a light absorbing agent composed of a second phosphonic acid and copper ions, a matrix resin such as a silicone resin is added to the solution D and stirred to obtain a solution I, and a solution H is further added to the solution I and stirred to prepare the light absorbing composition.

The light absorbing composition is applied to one main surface of the transparent dielectric substrate 20 to form a coating film. For example, a liquid light absorbing composition is applied to one main surface of the transparent dielectric substrate 20 by spin coating or application with a dispenser to form a coating film. Subsequently, the coating film is subjected to a predetermined heat treatment to cure the coating film. For example, the coating film is exposed to an environment at a temperature of 50 ℃ to 200 ℃. In order to sufficiently hydrolyze the alkoxysilane monomer contained in the light absorbing composition, the coating film is subjected to a humidification treatment as necessary. For example, the cured coating film is exposed to an environment having a temperature of 40 ℃ to 100 ℃ and a relative humidity of 40% to 100%. Thereby forming a repeating structure of siloxane bond (Si-O)_n. This enables the optical filter 1a to be manufactured. In general, in hydrolysis and polycondensation reactions of an alkoxysilane containing a monomer, these reactions are sometimes carried out by allowing the alkoxysilane and water to coexist in a liquid composition. However, when water is added to the light absorbing composition in advance in the production of an optical filter, the phosphate ester or the light absorbing agent is deteriorated in the formation process of the light absorbing layer, and there is a possibility that the light absorbing performance is lowered or the durability of the optical filter is impaired. Therefore, it is preferable to perform a humidifying treatment after curing the coating film by a predetermined heating treatment.

In the case where the transparent dielectric substrate 20 is a glass substrate, a resin layer containing a silane coupling agent may be formed between the transparent dielectric substrate 20 and the light absorbing layer 10 in order to improve adhesion between the transparent dielectric substrate 20 and the light absorbing layer 10.

< modification example >

The optical filter 1a can be modified in various ways. For example, the optical filter 1a may be changed to the optical filters 1B to 1E shown in fig. 1B to 1E, respectively. The optical filters 1b to 1e are configured in the same manner as the optical filter 1a, except for the case where it is specifically described. The same or corresponding components of the optical filters 1b to 1e as those of the optical filter 1a are denoted by the same reference numerals, and detailed description thereof is omitted. The description relating to the optical filter 1a also applies to the optical filters 1b to 1e, provided that there is no technical conflict.

As shown in fig. 1B, in an optical filter 1B according to another embodiment of the present invention, light absorbing layers 10 are formed on both main surfaces of a transparent dielectric substrate 20. Thus, the optical filter 1b can exhibit the optical performance of (i) to (iii) described above by using 2 light-absorbing layers 10 instead of 1 light-absorbing layer 10. The thicknesses of the light absorbing layers 10 on the two main surfaces of the transparent dielectric substrate 20 may be the same or different. That is, the light absorbing layers 10 are formed on both main surfaces of the transparent dielectric substrate 20 so that the thicknesses of the light absorbing layers 10 required for obtaining desired optical characteristics of the optical filter 1b are distributed uniformly or unequally. Thus, the thickness of each light absorbing layer 10 formed on one main surface of the transparent dielectric substrate 20 of the optical filter 1b is smaller than that of the optical filter 1 a. This can reduce the internal pressure of the coating film and prevent the occurrence of cracks. In addition, the time for applying the liquid light absorbing composition can be shortened, and the time for curing the coating film of the light absorbing composition can be shortened. By forming the light absorbing layers 10 on both main surfaces of the transparent dielectric substrate 20, warping in the optical filter 1b can be suppressed even when the transparent dielectric substrate 20 is thin. In this case, in order to improve the adhesion between the transparent dielectric substrate 20 and the light absorbing layer 10, a resin layer containing a silane coupling agent may be formed between the transparent dielectric substrate 20 and the light absorbing layer 10.

As shown in fig. 1C, an optical filter 1C according to another embodiment of the present invention includes an antireflection film 30. The antireflection film 30 is a film formed to form an interface between the optical filter 1c and the air, and is used to reduce reflection of light in the visible light range. The antireflection film 30 is formed of a dielectric material such as a resin, an oxide, or a fluoride. The antireflection film 30 may be a multilayer film formed by laminating two or more kinds of dielectrics having different refractive indices. In particular, the antireflection film 30 may be made of SiO₂Isorefractive index material and TiO₂Or Ta₂O₅A dielectric multilayer film made of a material having a high refractive index. In this case, fresnel reflection at the interface between the optical filter 1c and the air is reduced, and visibility of the optical filter 1c can be increasedThe amount of light in the light region. In this case, in order to improve the adhesion between the transparent dielectric substrate 20 and the light absorbing layer 10, a resin layer containing a silane coupling agent may be formed between the transparent dielectric substrate 20 and the light absorbing layer 10. In some cases, a resin layer containing a silane coupling agent may be formed between the light absorbing layer 10 and the antireflection film 30 in order to improve the adhesion of the antireflection film 30. The antireflection film 30 may be disposed on both main surfaces of the optical filter 1c, or may be disposed on only one main surface.

As shown in fig. 1D, an optical filter 1D according to another example of the present invention is constituted only by the light absorbing layer 10. The optical filter 1d can be manufactured, for example, as follows: the optical filter 1d is produced by applying the light absorbing composition to a predetermined substrate such as a glass substrate, a resin substrate, or a metal substrate (for example, a steel substrate or a stainless steel substrate) to form a coating film, curing the coating film, and then peeling the cured coating film from the substrate. The optical filter 1d can be manufactured by a melt molding method. The optical filter 1d is thin because it does not have the transparent dielectric substrate 20. Therefore, the optical filter 1d can contribute to the reduction in the back of the image pickup element and the optical system.

As shown in fig. 1E, an optical filter 1E according to another embodiment of the present invention includes a light absorbing layer 10 and a pair of antireflection films 30 disposed on both surfaces thereof. In this case, the optical filter 1e can contribute to the reduction of the back of the image pickup element and the optical system, and can increase the amount of light in the visible light region compared to the optical filter 1 d.

The optical filters 1a to 1e may be changed to include an infrared absorbing film or an ultraviolet absorbing film separately from the light absorbing layer 10 in order to improve the functionality thereof. The infrared absorbing film contains an organic infrared absorbing agent such as cyanine, phthalocyanine, squaraine, diimmonium, and azo, or an infrared absorbing agent composed of a metal complex. The infrared absorbing film contains 1 or 2 or more kinds of infrared absorbers selected from these infrared absorbers, for example. The organic infrared absorber has a small wavelength range (absorption band) of light that can be absorbed, and is suitable for absorbing light having a wavelength in a specific range.

The ultraviolet absorbing film contains an ultraviolet absorber such as a benzophenone-based, triazine-based, indole-based, merocyanine-based, or oxazole-based one. The ultraviolet absorbing film contains 1 or 2 or more ultraviolet absorbers selected from these ultraviolet absorbers, for example. These ultraviolet absorbers may include, for example, those which absorb ultraviolet rays in the vicinity of 300nm to 340nm and emit light (fluorescence) having a wavelength longer than the absorbed wavelength to function as a fluorescent agent or a fluorescent whitening agent, and the ultraviolet absorbing film can reduce the incidence of ultraviolet rays which cause deterioration of materials used for optical filters such as resins.

The transparent dielectric substrate 20 made of resin may contain the above-mentioned infrared absorber or ultraviolet absorber in advance. The infrared absorbing film and the ultraviolet absorbing film can be formed by, for example, forming a resin film containing an infrared absorber or an ultraviolet absorber. In this case, the resin needs to be transparent so that the infrared absorber or the ultraviolet absorber can be appropriately dissolved or dispersed. Examples of such resins include (poly) olefin resins, polyimide resins, polyvinyl butyral resins, polycarbonate resins, polyamide resins, polysulfone resins, polyethersulfone resins, polyamideimide resins, (modified) acrylic resins, epoxy resins, and silicone resins.

The optical filters 1a to 1e are disposed in front of (on the side close to the subject) an image sensor such as a CCD or a CMOS in the image pickup device, for example, in order to make the spectral sensitivity of the image sensor in the image pickup device closer to the human visual sensitivity.

In addition, the optical filter 1a can be used for manufacturing an information terminal with a camera, for example. In this case, the information terminal with a camera includes, for example, a lens system, an imaging element, and an optical filter 1 a. The image pickup element receives the light that has passed through the lens system. The optical filter 1a is disposed in front of the lens system and protects the lens system. In this case, the optical filter 1a functions as a cover of the lens system.

An example of a camera module 100 provided in an information terminal with a camera is shown. As shown in fig. 2, the camera module 100 includes, for example, a lens system 2, a low-pass filter 3, an image pickup device 4, a circuit board 5, an optical filter support case 7, and an optical system case 8 in addition to the optical filter 1 a. The periphery of the optical filter 1a is fitted into, for example, an annular recess in contact with an opening formed in the center of the optical filter support case 7. The optical filter support case 7 is fixed to the optical system case 8. The lens system 2, the low-pass filter 3, and the imaging element 4 are arranged in this order along the optical axis inside the optical system housing 8. The image pickup device 4 is, for example, a CCD or a CMOS. Light from an object is cut off by ultraviolet rays and infrared rays by the optical filter 1a, then condensed by the lens system 2, further passed through the low-pass filter 3, and enters the image pickup device 4. The electric signal generated by the image pickup device 4 is sent to the outside of the camera module 100 through the circuit board 5.

In the camera module 100, the optical filter 1a also functions as a cover (protective filter) that protects the lens system 2. In this case, a sapphire substrate is preferably used as the transparent dielectric substrate 20 in the optical filter 1 a. Since the sapphire substrate has high scratch resistance, it is preferable to dispose the sapphire substrate on the outer side (the side opposite to the side of the image pickup element 4), for example. Accordingly, the optical filter 1a has high scratch resistance against contact from the outside and the like, and has the optical performances (preferably, optical performances of (iv) to (xiii)) of the above (i) to (iii). This eliminates the need to dispose an optical filter for cutting off infrared rays or ultraviolet rays in the vicinity of the image pickup device 4, and makes it easy to reduce the back of the camera module 100. The camera module 100 shown in fig. 2 is a schematic diagram for illustrating the arrangement of the respective members, and the description has been given of a mode in which the optical filter 1a is used as a protection filter. The camera module using the optical filter 1a is not limited to the example shown in fig. 2 as long as the optical filter 1a can function as a protection filter, and the low-pass filter 3 may be omitted or another filter may be provided as necessary. Further, an antireflection film may be formed in contact with the light absorbing layer 10 of the optical filter 1 a.

Examples

The present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples. First, the evaluation methods of the optical filters of the examples and comparative examples will be described.

< measurement of transmittance Spectrum of optical Filter >

The transmittance spectra when light having a wavelength of 300nm to 1200nm was incident on the optical filters of examples and comparative examples were measured using an ultraviolet-visible spectrophotometer (product name: V-670, manufactured by JASCO corporation). The incident light angle with respect to the optical filter was changed from 0 ° to 65 ° at 5 ° intervals, and the transmittance spectrum at each angle was measured.

< measurement of thickness of light-absorbing layer >

The thicknesses of the optical filters of examples and comparative examples were measured by a digital micrometer. In the optical filters of examples and comparative examples, the thickness of the light absorbing layer in the optical filter was determined by subtracting the thickness of the glass substrate from the thickness of the optical filter measured by a digital micrometer.

< example 1>

Adding copper acetate monohydrate ((CH)₃COO)₂Cu·H₂O)1.125g was mixed with 60g of Tetrahydrofuran (THF), and stirred for 3 hours to obtain a copper acetate solution. Then, 0.412g of Plusturf A208N (manufactured by first Industrial pharmaceutical Co., Ltd.) as a phosphate ester compound was added to the obtained copper acetate solution and stirred for 30 minutes to obtain solution A. To phenylphosphonic acid (C)₆H₅PO(OH)₂) (manufactured by Nissan chemical industries Co., Ltd.) 0.441g of THF was added thereto and stirred for 30 minutes to obtain solution B-1. To 4-bromophenylphosphonic acid (C)₆H₄BrPO(OH)₂) (manufactured by Tokyo chemical industry Co., Ltd.) 0.661g of THF was added to stir for 30 minutes to obtain solution B-2. Next, liquid B-1 and liquid B-2 were mixed and stirred for 1 minute, and methyltriethoxysilane (MTES: CH) was added₃Si(OC₂H₅)₃) (manufactured by shin-Etsu chemical industries Co., Ltd.) 1.934g and tetraethoxysilane (TEOS: si (OC)₂H₅)₄) (Kishida Chemical company, special grade) 0.634, and further stirred for 1 minute to obtain solution B. AWhile stirring solution A, solution B was added to solution A, and the mixture was stirred at room temperature for 1 minute. Then, 25g of toluene was added to the solution, and the mixture was stirred at room temperature for 1 minute to obtain solution C. This solution C was put into a flask, and desolventization was carried out by a rotary evaporator (model: N-1110SF, manufactured by Tokyo chemical and mechanical instruments Co., Ltd.) while heating in an oil bath (model: OSB-2100, manufactured by Tokyo chemical and mechanical instruments Co., Ltd.). The oil bath was set to a temperature of 105 ℃. Then, the solution D after the solvent removal treatment was taken out from the flask. Liquid D, which is a dispersion of fine particles of copper phenyl phosphonate (absorbent) containing copper phenylphosphonate and copper 4-bromophenylphosphonate, was transparent, and the fine particles were well dispersed.

Copper acetate monohydrate 0.225g was mixed with THF 36g and stirred for 3 hours to obtain a copper acetate solution. Subsequently, 0.129g of Plysurf a208N 0.129 as a phosphate ester compound was added to the obtained copper acetate solution and stirred for 30 minutes to obtain a solution E. In addition, to n-butylphosphonic acid (C)₄H₉PO(OH)₂) (manufactured by Nippon chemical industry Co., Ltd.) 0.144g was added with THF 10g and stirred for 30 minutes to obtain solution F. While stirring solution E, solution F was added to solution E, and the mixture was stirred at room temperature for 1 minute. Then, 25G of toluene was added to the solution, and the mixture was stirred at room temperature for 1 minute to obtain solution G. The solution G was put into a flask, and desolventization was performed by a rotary evaporator while heating in an oil bath. The oil bath was set to a temperature of 105 ℃. Thereafter, the H solution after the solvent removal treatment was taken out from the flask. The liquid H as a dispersion of fine particles of copper butylphosphonate was transparent, and the fine particles were well dispersed.

To solution D was added 2.200g of a silicone resin (product name: KR-300, manufactured by shin-Etsu chemical Co., Ltd.) and the mixture was stirred for 30 minutes to obtain solution I. Solution H was added to solution I and stirred for 30 minutes to obtain a light absorbing composition (solution J) of example 1. The light absorbing composition (J liquid) of example 1 is shown in table 1 with the content of each component on a mass basis, and is shown in table 2 with the content of each component on a mass basis and the content of each phosphonic acid on a mass basis. The content of each phosphonic acid is determined by rounding off the 2 nd position after the decimal point, and therefore the total content may not be 100 mol%.

The light absorbing composition of example 1 was applied to a transparent glass substrate (product name: D263, manufactured by SCHOTT Co., Ltd.) made of borosilicate glass and having a size of 76mm × 76mm × 0.21mm in a range of 30mm × 30mm at the center of one main surface thereof using a dispenser to form a coating film. Trial and error was conducted so that the average transmittance of the optical filter at a wavelength of 700 to 730nm was about 1%, and the thickness of the coating film was determined. When the light absorbing composition is applied to the transparent glass substrate, a frame having an opening commensurate with the application range of the coating liquid is placed on the transparent glass substrate to block the coating liquid so that the coating liquid does not flow out. By adjusting the amount of the coating liquid, a coating film having a desired thickness can be obtained. Subsequently, the transparent glass substrate having the undried coating film was placed in an oven and subjected to a heat treatment at 85 ℃ for 6 hours to cure the coating film. Then, the transparent glass substrate on which the coating film was formed was left to stand in a constant temperature and humidity chamber set at a temperature of 85 ℃ and a relative humidity of 85% for 20 hours to perform a humidification treatment, thereby obtaining the optical filter of example 1 in which the light absorbing layer was formed on the transparent glass substrate. The wet treatment is performed to promote hydrolysis and polycondensation of the alkoxysilane contained in the light absorbing composition applied to the transparent glass substrate and to form a hard and dense matrix in the light absorbing layer. The thickness of the light absorbing layer of the optical filter of example 1 was 170 μm. The transmittance spectrum of the optical filter of example 1 at an incident angle of 0 ° to 65 ° was measured. Fig. 3 shows transmittance spectra at incident angles of 0 °, 40 °, 50 °, and 60 °. The results observed from the transmittance spectrum of the optical filter of example 1 at an incident angle of 0 ° are shown in tables 7 and 8. The "wavelength range having a transmittance of 78% or more" in table 8 is a wavelength range showing a spectral transmittance of 78% or more at a wavelength of 400nm to 600 nm. The "wavelength range having a transmittance of 1% or less" relating to the infrared region characteristics in table 8 is a wavelength range showing a spectral transmittance of 1% or less at a wavelength of 700nm to 1200 nm. The "wavelength range having a transmittance of 0.1% or less" relating to the infrared region characteristics in table 8 is a wavelength range showing a spectral transmittance of 0.1% or less at a wavelength of 700nm to 1200 nm. The "wavelength range having a transmittance of 1% or less" relating to the ultraviolet region characteristics in table 8 is a wavelength range showing a spectral transmittance of 1% or less at a wavelength of 300nm to 400 nm. The "wavelength range having a transmittance of 0.1% or less" related to the ultraviolet region characteristics in table 8 is a wavelength range showing a spectral transmittance of 0.1% or less at a wavelength of 300nm to 400 nm. These cases also apply to table 10, table 12, table 14, table 16, table 18, and table 20. Further, the results (incident angle: 0 ° to 65 °) observed from the transmittance spectra at the incident angle of 0 ° and 30 ° to 65 ° (interval of 5 °) of the optical filter of example 1 are shown in tables 11 and 12.

< examples 2 to 15>

Light absorbing compositions of examples 2 to 15 were prepared in the same manner as in example 1, except that the addition amount of each compound was adjusted as shown in table 1. Optical filters of examples 2 to 15 were produced in the same manner as in example 1, except that the light absorbing compositions of examples 2 to 15 were used instead of the light absorbing composition of example 1 and the thickness of the light absorbing layer was adjusted as shown in table 1. The content and content of each phosphonic acid based on the mass are shown in table 2. The content of each phosphonic acid is determined by rounding off the 2 nd position after the decimal point, and therefore the total content may not be 100 mol%. The transmittance spectrum of the optical filter of example 2 was measured at an incident angle of 0 ° to 65 °. The transmittance spectra at incident angles of 0 °, 40 °, 50 °, and 60 ° are shown in fig. 4. The results observed from the transmittance spectrum of the optical filter of example 2 at an incident angle of 0 ° are shown in tables 7 and 8. The results observed from the transmittance spectra of the optical filter of example 2 at incident angles of 0 ° and 30 ° to 65 ° (intervals of 5 °) are shown in tables 13 and 14. The results observed from the transmittance spectra at an incident angle of 0 ° of the optical filters of examples 3 to 15 are shown in tables 7 and 8.

< example 16>

The light absorbing composition of example 2 was applied to a transparent glass substrate (product name: D263, manufactured by SCHOTT Co., Ltd.) made of borosilicate glass and having a size of 76mm × 76mm × 0.21mm in a range of 30mm × 30mm at the center of one main surface thereof using a dispenser to form a coating film having a predetermined thickness. When the light absorbing composition is applied to the transparent glass substrate, a frame having an opening commensurate with the application range of the coating liquid is placed on the transparent glass substrate to block the coating liquid so that the coating liquid does not flow out. Subsequently, the transparent glass substrate having the undried coating film was placed in an oven and subjected to a heat treatment at 85 ℃ for 6 hours to cure the coating film. Then, the coating film was peeled off from the transparent glass substrate. The peeled coating film was left to stand in a constant temperature and humidity chamber set at 85 ℃ and 85% relative humidity for 20 hours and subjected to a humidification treatment, thereby obtaining an optical filter of example 16 composed only of a light absorbing layer. Only the thickness of the light absorbing layer was measured by measurement with a digital micrometer. As a result, the thickness of the optical filter of example 16 was 132 μm. The transmittance spectra of the optical filter of example 16 were measured at incident angles of 0 ° to 65 °. Fig. 5 shows transmittance spectra at incident angles of 0 °, 40 °, 50 °, and 60 °. The results observed from the transmittance spectrum at an incident angle of 0 ° of the optical filter of example 16 are shown in tables 7 and 8. The results observed from the transmittance spectra at incident angles of 0 ° and 30 ° to 65 ° (intervals of 5 °) of the optical filter of example 16 are shown in table 15 and table 16.

< example 17>

The light absorbing composition of example 2 was applied using a dispenser to a range of 30mm × 30mm in the central portion of one main surface of a transparent glass substrate (product name: D263, manufactured by SCHOTT corporation) formed of borosilicate glass having a size of 76mm × 76mm × 0.21mm, to form a coating film having a thickness smaller than that of the coating film in example 2. When the light absorbing composition is applied to the transparent glass substrate, a frame having an opening commensurate with the application range of the coating liquid is placed on the transparent glass substrate to block the coating liquid so that the coating liquid does not flow out. Subsequently, the transparent glass substrate having the undried coating film was placed in an oven and subjected to a heat treatment at 85 ℃ for 6 hours to cure the coating film. Next, the light absorbing composition of example 2 was applied to the central portion of the other main surface of the transparent glass substrate in the range of 30mm × 30mm using a dispenser to form a coating film having a thickness smaller than that of the coating film in example 2. When the light absorbing composition is applied to the transparent glass substrate, a frame having an opening commensurate with the application range of the coating liquid is placed on the transparent glass substrate to block the coating liquid so that the coating liquid does not flow out. Subsequently, the transparent glass substrate having the undried coating film was placed in an oven and subjected to a heat treatment at 85 ℃ for 6 hours to cure the coating film. Next, the transparent glass substrate having the coating films formed on both main surfaces thereof was left in a constant temperature and humidity chamber set at a temperature of 85 ℃ and a relative humidity of 85% for 20 hours to be subjected to a humidification treatment, thereby obtaining the optical filter of example 17 in which the light absorbing layers were formed on both surfaces of the transparent glass substrate. The total thickness of the light-absorbing layers formed on both surfaces of the transparent glass substrate was 193 μm. The transmittance spectrum of the optical filter of example 17 was measured at an incident angle of 0 ° to 65 °. The transmittance spectra at incident angles of 0 °, 40 °, 50 °, and 60 ° are shown in fig. 6. The results observed from the transmittance spectrum at an incident angle of 0 ° of the optical filter of example 17 are shown in tables 7 and 8. The results observed from the transmittance spectra at incident angles of 0 °, 30 ° to 65 ° (intervals of 5 °) of the optical filter of example 17 are shown in tables 17 and 18.

< example 18>

A light absorbing composition of example 18 was prepared in the same manner as in example 1 except that Plysurf a208F (manufactured by first industrial pharmaceutical company) was used as the phosphate ester compound instead of Plysurf a208N, and the addition amount of each compound was adjusted as shown in table 1. An optical filter of example 18 was produced in the same manner as in example 1, except that the light-absorbing composition of example 18 was used instead of the light-absorbing composition of example 1, and the thickness of the light-absorbing layer was adjusted to 198 μm. The transmittance spectra of the optical filter of example 18 at an incident angle of 0 ° to 65 ° were measured, and the results observed from the transmittance spectra at an incident angle of 0 ° are shown in tables 7 and 8. The results observed from the transmittance spectra at incident angles of 0 °, 30 ° to 65 ° (intervals of 5 °) of the optical filter of example 18 are shown in tables 19 and 20.

< example 19>

Except that 4-fluorophenylphosphonic acid (C) is used₆H₄FPO(OH)₂) A light-absorbing composition of example 19 was prepared in the same manner as in example 1 except that the amount of each compound added was adjusted as shown in table 1 in place of 4-bromophenylphosphonic acid (manufactured by tokyo chemical industry co.). An optical filter of example 19 was produced in the same manner as in example 1, except that the light-absorbing composition of example 19 was used instead of the light-absorbing composition of example 1, and the thickness of the light-absorbing layer was adjusted to 168 μm. The transmittance spectra of the optical filter of example 19 were measured, and the results observed from the transmittance spectra at an incident angle of 0 ° are shown in tables 7 and 8.

< examples 20 to 35>

Optical filters of examples 20 to 35 were produced in the same manner as in example 2, except that the conditions for the humidification treatment of the dried coating film were changed as shown in table 3 and the thickness of the light absorbing layer was adjusted as shown in table 3. The transmittance spectra of the optical filters of examples 20 to 35 were measured. The transmittance spectra of the optical filters of examples 20 to 22 at an incident angle of 0 ° are shown in fig. 7 to 9, respectively. The results observed from the transmittance spectra at an incident angle of 0 ° of the optical filters of examples 20 to 35 are shown in tables 7 and 8.

< example 36>

An optical filter of example 36 was fabricated in the same manner as in example 2, except that a sapphire substrate having a thickness of 0.3mm was used instead of the transparent glass substrate used in example 2, and the thickness of the light absorbing layer was adjusted to 168 μm. The transmittance spectrum of the optical filter of example 36 was measured. Fig. 10 shows a transmittance spectrum of the optical filter of example 36 at an incident angle of 0 °. The results observed from the transmittance spectra at an incident angle of 0 ° are shown in tables 7 and 8.

< comparative example 1>

Liquid D (dispersion of fine particles of phenyl copper phosphonate) of comparative example 1 was prepared in the same manner as in example 1, except that the addition amount of each compound was adjusted as shown in tables 4 and 5. To the solution D of comparative example 1 was added 2.200g of a silicone resin (product name: KR-300, manufactured by shin-Etsu chemical industries, Ltd.) and the mixture was stirred for 30 minutes to obtain a light-absorbing composition of comparative example 1. An optical filter of comparative example 1 was produced in the same manner as in example 1, except that the light-absorbing composition of comparative example 1 was used instead of the light-absorbing composition of example 1, and the thickness of the light-absorbing layer was adjusted to 126 μm. The transmittance spectrum of the optical filter of comparative example 1 was measured. The results obtained from the observation of the transmittance spectrum of the optical filter of comparative example 1 at an incident angle of 0 ° are shown in tables 9 and 10. Further, based on the results of the transmittance spectrum measurement of the optical filter of comparative example 1 at an incident angle of 0 °, the transmittance spectrum when the thickness of the light absorbing layer of the optical filter of comparative example 1 was changed to 200 μm was calculated, and the results obtained by observation from the transmittance spectrum are shown in table 9 and table 10 as comparative calculation example 1.

< comparative example 2>

Liquid D (dispersion of fine particles of copper phenyl phosphonate) of comparative example 2 was prepared in the same manner as in example 1, except that the addition amount of each compound was adjusted as shown in tables 4 and 5. 4.400g of a silicone resin (product name: KR-300, manufactured by shin-Etsu chemical industries, Ltd.) was added to the solution D of comparative example 2, followed by stirring for 30 minutes to obtain a light-absorbing composition of comparative example 2. An optical filter of comparative example 2 was produced in the same manner as in example 1, except that the light absorbing composition of comparative example 2 was used instead of the light absorbing composition of example 1, the thickness of the light absorbing layer was adjusted to 217 μm, and the conditions of the heating treatment and the humidifying treatment for curing the coating film were changed as shown in table 6. The transmittance spectrum of the optical filter of comparative example 2 was measured. The results obtained from the observation of the transmittance spectrum of the optical filter of comparative example 2 at an incident angle of 0 ° are shown in tables 9 and 10. Further, based on the result of the transmittance spectrum measurement of the optical filter of comparative example 2 at an incident angle of 0 °, the transmittance spectrum when the thickness of the light absorbing layer of the optical filter of comparative example 2 was changed to 347 μm was calculated, and the results obtained by observation from the transmittance spectrum are shown in table 9 and table 10 as comparative calculation example 2.

< comparative example 3>

1.125g of copper acetate monohydrate was mixed with 60g of THF, and stirred for 3 hours to obtain a copper acetate solution. Then, 0.624g of Plyschf A208F (first Industrial pharmaceutical Co., Ltd.) was added to the obtained copper acetate solution and stirred for 30 minutes to obtain solution A. To 0.832g of phenylphosphonic acid (manufactured by Nissan chemical industries, Ltd.) was added 10g of THF, and the mixture was stirred for 30 minutes to obtain a solution B-1. To the B-1 solution were added 1.274g of MTES (manufactured by shin Etsu Chemical Co.) and 1.012g of TEOS (special grade manufactured by Kishida Chemical Co.) and stirred for further 1 minute to obtain a B solution. While stirring solution A, solution B was added to solution A, and the mixture was stirred at room temperature for 1 minute. Then, 25g of toluene was added to the solution, and the mixture was stirred at room temperature for 1 minute to obtain solution C. This solution C was put into a flask, and desolventization was carried out by a rotary evaporator (model: N-1110SF, manufactured by Tokyo chemical and mechanical instruments Co., Ltd.) while heating in an oil bath (model: OSB-2100, manufactured by Tokyo chemical and mechanical instruments Co., Ltd.). The oil bath was set to a temperature of 105 ℃. Thereafter, the solution D of comparative example 3 after the solvent removal treatment was taken out from the flask. The liquid D (dispersion of fine particles of copper phenylphosphonate) of comparative example 3 was transparent, and the fine particles were well dispersed.

4.400g of a silicone resin (product name: KR-300, manufactured by shin-Etsu chemical industries, Ltd.) was added to the solution D of comparative example 3, followed by stirring for 30 minutes to obtain a light-absorbing composition of comparative example 3. An optical filter of comparative example 3 was produced in the same manner as in example 1, except that the light absorbing composition of comparative example 3 was used in place of the light absorbing composition of example 1, the thickness of the light absorbing layer was adjusted to 198 μm, and the conditions of the heat treatment for curing the coating film were adjusted as shown in table 6. The transmittance spectrum of the optical filter of comparative example 3 was measured. The results obtained from the observation of the transmittance spectrum of the optical filter of comparative example 3 at an incident angle of 0 ° are shown in tables 9 and 10. Further, based on the result of the transmittance spectrum measurement when the incident angle of the optical filter of comparative example 3 was 0 °, the transmittance spectrum when the thickness of the light absorbing layer of the optical filter of comparative example 3 was changed to 303 μm was calculated, and the results obtained by observation from the transmittance spectrum are shown in table 9 and table 10 as comparative calculation example 3.

< comparative example 4>

An optical filter of comparative example 4 was produced in the same manner as in example 2, except that the thickness of the light absorbing layer was adjusted to 191 μm and the humidification treatment of the coating film was not performed. The transmittance spectrum of the optical filter of comparative example 4 was measured. The results obtained from the observation of the transmittance spectrum of the optical filter of comparative example 4 at an incident angle of 0 ° are shown in tables 9 and 10. Further, a transmittance spectrum obtained when the thickness of the light absorbing layer of the optical filter of comparative example 4 was changed to 148 μm was calculated based on the transmittance spectrum of the optical filter of comparative example 4 at an incident angle of 0 °, and the results obtained by observation from the transmittance spectrum are shown in tables 9 and 10 as comparative calculation example 4.

< comparative examples 5 and 6>

Optical filters of comparative examples 5 and 6 were produced in the same manner as in example 2, except that the thickness of the light absorbing layer was adjusted as shown in table 9 and the humidification treatment of the coating film was adjusted as shown in table 6. The transmittance spectra of the optical filters of comparative examples 5 and 6 were measured. The results obtained from the observation of the transmittance spectrum of the optical filter of comparative example 5 at an incident angle of 0 ° are shown in tables 9 and 10. Further, a transmittance spectrum obtained when the thickness of the light absorbing layer of the optical filter of comparative example 5 was changed to 155 μm was calculated based on the transmittance spectrum of the optical filter of comparative example 5 at an incident angle of 0 °, and the results obtained by observation from the transmittance spectrum are shown in tables 9 and 10 as comparative calculation example 5. The results obtained from the observation of the transmittance spectrum of the optical filter of comparative example 6 at an incident angle of 0 ° are shown in tables 9 and 10. Further, a transmittance spectrum obtained when the thickness of the light absorption layer of the optical filter of comparative example 6 was changed to 161 μm was calculated based on the transmittance spectrum of the optical filter of comparative example 6 at an incident angle of 0 °, and the results obtained by observation from the transmittance spectrum are shown in tables 9 and 10 as comparative calculation example 6.

< comparative example 7>

Liquid D (dispersion of fine particles of phenyl copper phosphonate) of comparative example 7 was prepared in the same manner as in comparative example 1. Copper acetate monohydrate 0.225g was mixed with THF 36g and stirred for 3 hours to obtain a copper acetate solution. Then, 0.178g of Plyschf A208F (manufactured by first Industrial pharmaceutical Co., Ltd.) as a phosphate ester compound was added to the obtained copper acetate solution and stirred for 30 minutes to obtain solution E. Further, to 0.134g of n-butylphosphonic acid (manufactured by Nippon chemical industries, Ltd.) was added 10g of THF, and the mixture was stirred for 30 minutes to obtain solution F. While stirring solution E, solution F was added to solution E, and the mixture was stirred at room temperature for 1 minute. Then, 25G of toluene was added to the solution, and the mixture was stirred at room temperature for 1 minute to obtain solution G. The solution G was put into a flask, and desolventization was performed by a rotary evaporator while heating in an oil bath. The oil bath was set to a temperature of 105 ℃. Thereafter, the desolvated liquid H of comparative example 7 was taken out from the flask. To the solution D of comparative example 7 was added 2.200g of a silicone resin (product name: KR-300, manufactured by shin-Etsu chemical Co., Ltd.) and the mixture was stirred for 30 minutes to obtain solution I of comparative example 7. Although solution H of comparative example 7 was added to solution I of comparative example 7 and stirred, copper phosphonate particles aggregated, and a light absorbing composition having high transparency could not be obtained.

< comparative example 8>

An attempt was made to prepare a light absorbing composition containing only n-butylphosphonic acid as phosphonic acid and no alkoxysilane monomer in the amounts shown in table 4, but copper phosphonate particles were aggregated, and a uniform light absorbing composition having high transparency could not be obtained.

According to Table 7, the optical filters of examples 1 to 36 satisfy the above conditions (i) to (vii). In addition, according to table 11, table 13, table 15, table 17 and table 19, (viii) the differences between the absolute values of the second IR cut-off wavelength and the first IR cut-off wavelength are 3nm (example 1), 4nm (example 2), 4nm (example 16), 3nm (example 17), 4nm (example 18), (ix) the differences between the absolute values of the third IR cut-off wavelength and the first IR cut-off wavelength are 6nm (example 1), 7nm (example 2), 7nm (example 16), 6nm (example 17), 7nm (example 18), (x) the differences between the absolute values of the second UV cut-off wavelength and the first UV cut-off wavelength are 2nm (example 1), 3nm (example 2), 3nm (example 16), 3nm (example 17), 3nm (example 18), (xi) the differences between the absolute values of the third UV cut-off wavelength and the first UV cut-off wavelength are 3nm (example 1), (3 nm (example 1), The optical filters of examples 1, 2, 16, 17 and 18 further satisfy the above-described conditions (viii) to (xi) at 5nm (example 2), 5nm (example 16), 5nm (example 17) and 4nm (example 18). Further, the optical filters of examples 3 to 15 and examples 19 to 36 also satisfy the conditions (viii) to (xi) described above, based on the transmittance spectra at the incident angle of 0 ° to 65 ° (not shown).

From table 9, the optical filter of comparative example 1 does not satisfy the conditions (ii), (vi), and (vii) described above, and does not have the desired characteristics in the infrared region. Further, according to comparative calculation example 1, it is suggested that the characteristics in the infrared region can be improved by increasing the thickness of the light absorbing layer, but the first IR cut-off wavelength is short, and the optical performance of (iii) cannot be realized. This suggests that an optical filter satisfying all of the conditions (i) to (iii) above could not be produced even when the light absorbing composition of comparative example 1 was used. Similarly, from the results of comparative example 2 and comparative calculation example 2, and comparative example 3 and comparative calculation example 3 in table 9, it is suggested that an optical filter satisfying all the conditions (i) to (iii) described above cannot be manufactured even when the light absorbing compositions of comparative examples 2 and 3 are used.

According to table 9, the optical filter of comparative example 4 does not satisfy the conditions (i) and (iii) described above. According to comparative calculation example 4, it is suggested that the average transmittance at a wavelength of 450 to 600nm can be improved by reducing the thickness of the light absorbing layer, but the IR cut-off wavelength hardly changes, and the maximum transmittance at a wavelength of 750 to 1080nm also increases. Therefore, it is suggested that an optical filter satisfying all the conditions (i) to (iii) above cannot be manufactured by the method for manufacturing an optical filter of comparative example 4. It is suggested that hydrolysis and polycondensation of the alkoxysilane monomer contained in the light absorbing composition are promoted by the humidification treatment, and the humidification treatment affects the transmittance spectrum of the optical filter in addition to advancing the curing of the light absorbing layer.

According to table 9, the optical filter of comparative example 5 does not satisfy the condition (iii) above. According to comparative calculation example 5, it is suggested that the IR cut-off wavelength can be increased by decreasing the thickness of the light absorbing layer, but the maximum transmittance at a wavelength of 750 to 1080nm is also increased. Therefore, it is suggested that an optical filter satisfying all the conditions (i) to (iii) above cannot be manufactured by the method for manufacturing an optical filter of comparative example 5. In particular, it is suggested that the conditions of the humidification treatment in comparative example 5 are insufficient.

According to table 9, the optical filter of comparative example 6 does not satisfy the conditions (i) and (iii) described above. According to comparative calculation example 6, it is suggested that the IR cut-off wavelength can be increased by decreasing the thickness of the light absorbing layer, but the maximum transmittance at a wavelength of 750 to 1080nm is also increased. Therefore, it is suggested that an optical filter having all of the optical performances of the above (i) to (iii) cannot be manufactured by the method for manufacturing an optical filter of comparative example 6. In particular, it is suggested that the conditions of the humidification treatment in comparative example 6 are insufficient.

As shown in Table 2, in the light absorbing compositions of examples 3 to 5, the content of n-butylphosphonic acid was the highest in the light absorbing composition of example 3, and the content of n-butylphosphonic acid was the lowest in the light absorbing composition of example 5. From this point and table 8, it is suggested that when the content of the alkyl phosphonic acid in the light absorbing composition is increased, the wavelength range in which the spectral transmittance at a wavelength of 700 to 1200nm is 1% or less and the wavelength range in which the spectral transmittance is 0.1% or less are expanded toward the long wavelength side. The same can be said for examples 6 to 8, examples 9 and 10, and examples 11 to 15.

As shown in table 2, in the light absorbing compositions of examples 11 to 15, the content of n-butylphosphonic acid was the highest in the light absorbing composition of example 11, the content of n-butylphosphonic acid was the second highest in the light absorbing composition of example 12, the content of n-butylphosphonic acid was the third highest in the light absorbing composition of example 13, and the content of n-butylphosphonic acid was the lowest in the light absorbing composition of example 15. According to the results of examples 11 to 15 in Table 7, the maximum transmittance of the optical filter at the wavelength of 1000 to 1100nm and the maximum transmittance of the optical filter at the wavelength of 1100 to 1200nm were the lowest in example 11, the second lowest in example 12, the third lowest in example 13, and the highest in example 15. This suggests that the light absorbing composition can have improved wavelength shielding properties in the infrared region by increasing the content of the alkyl sulfonic acid in a predetermined range.

As shown in Table 2, of the light absorbing compositions of examples 7, 10 and 13, the light absorbing composition of example 7 had the highest content of 4-bromophenyl phosphonic acid, and the light absorbing composition of example 13 had the lowest content of 4-bromophenyl phosphonic acid. From the results of examples 7, 10 and 13 in table 7, the UV cut-off wavelength increased as the content of 4-bromophenylphosphonic acid in the light absorbing composition increased. This suggests that optical properties such as the UV cut-off wavelength of the optical filter can be optimized by adjusting the content of 4-bromophenylphosphonic acid in the light absorbing composition.

Light absorbing compositions used for producing the optical filters of examples 20 to 35 and comparative examples 4 to 6 were prepared in the same manner as the light absorbing composition of example 2, but the optical filters of these examples and comparative examples had optical properties different from those of the optical filter of example 2 as shown in tables 7 to 10. As described above, the wet treatment was performed to promote hydrolysis and polycondensation of the alkoxysilane contained in the light absorbing composition, but the average transmittance and IR cut-off wavelength at a wavelength of 450 to 600nm were different in the optical filters of the examples and comparative examples according to the manner of the wet treatment.

According to the results of comparative calculation examples 4 to 6 in table 9, although the UV cut-off wavelength can be adjusted by changing the thickness of the light absorbing layer, it is difficult to make the IR cut-off wavelength fall within a desired range while satisfying other optical performances (i) to (xi) according to the manufacturing methods of the optical filters of comparative examples 4 to 6. Therefore, the amount of water vapor in the atmosphere to which the object to be treated was exposed (the amount of water vapor exposed) in the humidification treatment of each of the examples and some of the comparative examples was determined as follows. The results are shown in tables 3 and 6. According to the approximate formula of Tetens: e-6.11 × 10^{(7.5t/(t+237.3))}The temperature t DEG C is determined]Saturated water vapor pressure e [ hPa ]]. According to the formula

From the saturated water vapour pressure e [ hPa]And relative humidity

[％]Determining the density of water vapourρv[g/m³]. The amount of water vapor is multiplied by the time [ mol/m ]³Hour(s)]Defined as the amount of water vapor exposed. As shown in tables 3 and 6, it is suggested that good optical properties can be obtained when the relative humidity is 70% or more and the treatment time is 1 hour or more at a temperature of 60 ℃ or more in the humidification treatment. The treatment conditions correspond to 5.0[ mol/m ]³Hour(s)]The above conditions of the amount of exposure water vapor suggest that even in the case where the temperature of the humidification treatment is low at 40 ℃ and the relative humidity is 70% and in the case where the temperature of the humidification treatment is low at 60 ℃ and the relative humidity is 40%, good optical performance can be obtained by extending the treatment time so that the amount of exposure water vapor is equal. These results suggest that, from the viewpoint of efficiently providing the optical filter with good optical performance, it is preferable to perform the humidification treatment for a short time in an environment of a temperature of 60 ℃ or higher and a relative humidity of 70% or higher.

[ Table 1]

[ Table 2]

[ Table 3]

[ Table 4]

[ Table 5]

[ Table 6]

[ Table 7]

[ Table 8]

[ Table 9]

[ Table 10]

[ Table 11]

[ Table 12]

[ Table 13]

[ Table 14]

[ Table 15]

[ Table 16]

[ Table 17]

[ Table 18]

[ Table 19]

[ Table 20]

Claims

1. An optical filter, wherein,

the optical filter is provided with a light absorption layer,

2. The optical filter of claim 1,

(iv) has a spectral transmittance of 1% or less at a wavelength of 300 to 350 nm.

3. The optical filter according to claim 2, wherein the condition (iv) is satisfied by the light absorption layer.

4. The optical filter of claim 1 or 2,

(v) has a spectral transmittance that increases with increasing wavelength at a wavelength of 350nm to 450nm, and a first UV cut-off wavelength that exhibits a spectral transmittance of 50% at a wavelength of 350nm to 450nm exists in a range of 380nm to 430 nm.

5. The optical filter according to claim 4, wherein the condition (v) is satisfied by the light absorbing layer.

6. The optical filter according to any one of claims 1 to 5, wherein the light absorbing layer contains a light absorbing agent formed of phosphonic acid and copper ions.

7. The optical filter of claim 6, wherein the phosphonic acid comprises a first phosphonic acid having an aryl group.

8. The optical filter according to claim 7, wherein the first phosphonic acid has a halophenyl group in which at least 1 hydrogen atom of the phenyl group is substituted with a halogen atom in a part thereof.

9. The optical filter of claim 7 or 8, wherein the phosphonic acid further comprises a second phosphonic acid having an alkyl group.

10. The optical filter according to any one of claims 1 to 9, further comprising a transparent dielectric substrate covered with the light absorption layer.

11. An information terminal with a camera, comprising:

a lens system;

an image pickup element that receives the light that has passed through the lens system; and

the optical filter of any one of claims 1-10 disposed in front of and protecting the lens system.